Rotation-linear motion conversion apparatuses are used in steering apparatuses that arbitrarily change the travel direction of a vehicle.
A rotation-linear motion conversion apparatus includes a pinion shaft in which a pinion gear is formed and a rack bar in which a rack gear that engages with the pinion gear is formed. A rack and pinion apparatus converts a rotation motion of the pinion shaft into a linear motion of the rack bar by the action between the pinion gear and the rack gear.
When a steering wheel is rotated, the pinion shaft is rotated via a steering shaft. In accordance with the rotation of the pinion shaft, the rack bar is reciprocated in the vehicle width direction and changes the direction (travel direction) of a tire (wheel) via a link member.